This invention relates to an intraocular lens suitable for use as an artificial lens implant in either the anterior or posterior chamber of the human eye. Particularly, this invention relates to an intraocular lens having at least one asymmetric resilient spring-like support loop which contains sloped portions which provide the lens with a vault and outer contact portion for holding the lens in place in the eye.
Intraocular lens implantation after cataract surgery has come into common usage because of the improved vision obtained thereby over the alternatives of contact lenses or spectacles. Intraocular lenses have been implanted in both the posterior as well as the anterior chambers of the eye. In general format, an intraocular lens consists of a lens body and a plurality of support members usually projecting from different sides of the lens body for use in supporting the lens in position in the eye. Within the basic format, however, several different designs of intraocular lenses are currently available. In most of these, the position fixation elements or support means are in the form of rigid loops, arms, plates, legs, and the like, such as exemplified by the rigid loops 12 and 13 in Jensen U.S. Pat. No. 4,110,848 and by the rigid plates 12 and 13 of Kelman U.S. Pat. No. 4,092,743. Both the Jensen and the Kelman patents disclose rigid loops or plates which extend through the iris. Prongs extending through the iris are disclosed as fixation means in the Flom U.S. Pat. No. 3,866,249. Jensen et al U.S. Pat. No. 3,994,027 and Payman et al U.S. Pat. No. 4,073,015 both disclose rigid support loops engaging the anterior capsule wall.
A recent more flexible posterior chamber lens is disclosed by Shearing U.S. Pat. No. 4,159,546 in which J-shaped elastic support members extend outwardly from opposite peripheral edges of the lens to engage the ciliary body, or possibly the lens capsule, to support the lens in position.
It has also been proposed by Grinder, in Ser. No. 113,682, to employ flexible capsule engaging support loops of a shape similar to element 12 of the Kelman U.S. Pat. No. 4,092,743 with two of such loops extending from opposite sides of the lens body. Additionally, Sheets, in U.S. Ser. No. 071,375, employs flexible support loops for engagement with the lens capsule.
Furthermore, it is known to fashion the support members of the lens so that they have sloped or inclined portions which result in the portions of the support members which are to contact the eye being non-planar with the lens body. Such lenses are said to be "vaulted" and are disclosed in, for example, U.S. Pat. Nos. 2,834,023; 4,092,743; 4,110,848 and 4,134,161.
FIGS. 6 and 7 illustrate prior art lenses having support loops which contain sloped or vaulted portions. Referring to FIG. 6, an elevational view of a vaulted two-loop lens 81 is shown. The lens of FIG. 6 includes a lens body 82 which has a convex anterior surface and a flat posterior surface, and identical symmetric support loops 86 and 87 made of a polymeric material. Loops 86 and 87 have end portions 89 and 95 attached to lens body 82 and columnar leg portions 90 and 94 which extend from end portions 89 and 95 respectively. Loops 86 and 87 also have transverse portion 91 which extends transversely between leg portions 90 and 94 and contains a first contact portion 92 and second contact portion 93. Loops 86 and 87 contain sloped portions lying between imaginary lines G and H which are inclined somewhat posteriorly to lens body 82. These sloped portions are inclined such that transverse portion 91 lies in a plane parallel to the posterior of the lens body 82. Imaginary lines G and H are parallel to an imaginary line I which is perpendicular to both columnar leg portions 90 and 94 and intersects and is perpendicular to the geometric axis 88 of the lens body 82. The lens illustrated by FIG. 6 is commercially available as the "Leiske .sup.R Physioflex .sup.R Style 10 Anterior Chamber Lens" from Surgidev Corporation.
Referring to FIG. 7, an elevational view of another vaulted loop lens of the prior art is shown. The lens 101 includes a lens body 102 which is identical to the lens body 82, and identical support loops 106 and 107 which are made of polymeric material. The loops 106 and 107 have portions 109 and 115 attached to the lens body and columnar leg portions 110 and 114 which extend from end portions 109 and 115 respectively. Connecting legs 110 and 114 is a transverse portion comprising a first contact foot portion 111 and a second contact foot portion 113 with each foot portion being of arcuate configuration having a center of curvature between it and the lens body 102, as is apparent from an inspection of FIG. 7. Contact portions 111 and 113 are connected by an inwardly extending oppositely curved arcuate connector portion 112 which has a center of curvature positioned outwardly from itself with respect to the lens body 102.
Loops 106 and 107 also contain sloped portions lying between imaginary lines J and K, which are inclined somewhat posteriorly to lens body 102. These sloped portions are inclined such that portions 111, 112, and 113 lie in a plane which is substantially parallel to the posterior surface of the lens body 102. Imaginary lines J and K are parallel to an imaginary line L which is perpendicular to the columnar leg portions 110 and 114 and intersects the geometric axis 108 of the lens body 102. The lens illustrated by FIG. 7 is commercially available as the "Anterior Chamber Liteflex .sup.R Style 70 Intraocular Lens" from McGhan/3M.
Notwithstanding the great strides made in lens implantation, as evidenced by the thousands of successful lens implantations, complications in individual cases continue to arise in a small percentage of the cases. For example, the lenses of the prior art are relatively unstable and are easily mispositioned which may cause them to come in contact with the cornea or iris, thereby causing cell death or erosion of these parts of the eye. Improper sizing and excessive weight of the lens and support elements also cause subsequent mispositioning of the lens in some instances. Additionally, the use of sutures in other similar connectors engaging viable portions of the eye may cause cell death or erosion of these parts of the eye.
This invention provides an improved and more stable intraocular lens for positioning in either the anterior or posterior chamber of the eye. The lens of this invention is easy to implant and has stability without suturing.